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Cardiovascular System - Coggle Diagram
Cardiovascular System
MACROSCOPIC STRUCTURE OF THE HEART
Location and Shape
Lies in the middle mediastinum, positioned between the lungs, slightly to the left of the sternum.
Shape is often described as a quadrangular pyramid, with the apex pointing toward the left anterior chest.
Chambers & Major Vessels
Four Chambers: Right atrium, right ventricle, left atrium, and left ventricle.
Venous Inflow: Superior & inferior vena cavae drain into the right atrium ; pulmonary veins drain into the left atrium.
Arterial Outflow: Pulmonary trunk/artery exits the right ventricle ; the Aorta exits the left ventricle.
Heart Wall Layers (Outer to Inner)
Epicardium (Visceral Pericardium): Outermost layer; contains connective tissue, fat, and coronary vessels.
Myocardium: The thickest layer; consists of cardiac muscle cells (cardiomyocytes) and is responsible for pumping.
Endocardium: The smooth inner lining made of endothelial cells, lining the chambers and valves.
Internal Structures
Fibrous Skeleton: Provides structural support for the valves. It electrically insulates the atria from the ventricles, guiding conduction.
Valves: Include the tricuspid, pulmonary, mitral, and aortic valves.
STRUCTURE OF CARDIAC MUSCLE
General Characteristics
It is an involuntary muscle.
It is striated, like skeletal muscle, due to the organized actin-myosin filaments.
Fibers are branched and typically contain one or two centrally located nuclei.
Cells contain numerous mitochondria (25-30% of cell volume) for a continuous energy supply.
Intercalated Discs
Specialized junctions connecting cardiac muscle cells end-to-end.
Desmosomes: Anchor cells together to prevent separation during forceful contractions.
Gap Junctions: Allow ions to move between cells, enabling electrical coupling and uniform contraction (functional syncytium).
Physiological Properties
Automaticity: Some cells spontaneously generate impulses.
Rhythmicity: Ensures a regular cycle of contraction.
High Fatigue Resistance: Achieved through an abundance of mitochondria and a rich blood supply.
VASCULATURE OF THE HEART (CORONARY CIRCULATION)
Coronary Arteries (Supply)
Left Coronary Artery (LCA): Divides into the anterior interventricular (LAD) and circumflex branches. The LAD supplies the walls of both ventricles and the septum.
Right Coronary Artery (RCA): Supplies the right atrium. Branches include the Posterior Interventricular branch and the Marginal branch, which supplies the right ventricle myocardium.
Coronary Veins (Drainage)
Coronary Sinus: A large vascular sinus on the posterior surface where most deoxygenated blood drains into.
Great Cardiac Vein: Drains areas supplied by the LCA, including the left and right ventricles and left atrium.
Middle Cardiac Vein: Drains areas supplied by the posterior interventricular branch of the RCA.
HEMODYNAMICS
Types of Arterial Pressure
Systolic Pressure: The highest pressure when the heart contracts and pumps blood out (the top number).
Diastolic Pressure: The lowest pressure when the heart rests and refills between beats (the bottom number).
Mean Arterial Pressure (MAP): The average pressure in the arteries during a cardiac cycle, which is a key indicator of blood flow to tissues.
Variables Affecting Blood Flow/Pressure
Blood Viscosity: Thickness of the blood; increased viscosity raises resistance and blood pressure.
Blood Volume: Higher circulating volume increases cardiac output and arterial pressure.
Elasticity/Compliance of Vessel Walls: Vessel elasticity helps maintain continuous blood flow; decreased elasticity leads to higher systolic pressure.